While it is generally believed by the archaeological community that the Aurignacian tool making culture that existed until about 26,000 years was Cro-Magnon, a 2004 study suggested the possibility that the civilization was, in fact, "the last hurrah" of the Neanderthals' civilization and racial existence.[1] The culture and loci of the finds better match Auel's portrayed homelands for the Cro-Magnon cultures in her works: the plains of the Ukraine and Danube valleys and across the Alps to western France, which is consistent with mainstream archaeological thinking.

Surviving Cro-Magnon artifacts and features include huts, cave paintings, carvings and antler-tipped spears. The remains of tools suggest that they knew how to make woven clothing. They had huts, constructed of rocks, clay, bones, branches, and animal hide/fur. These early humans used manganese and iron oxides to paint pictures and may have created the first calendar around 15,000 years ago.[2]

The flint tools found in association with the remains at the first Cro-Magnon site have associations with the Aurignacian culture that Lartet had identified a few years before he found the skeletons.

If the Cro-Magnons and Neanderthals co-existed in the same regions at the same time, they might be presumed to have come in contact with one another; the former are often credited with causing the latter's extinction, although modern humans seem to have coexisted with Neanderthals for up to 60,000 years in the Levant[3] and for more than 15,000 years in France.[4]

Auel's research led to the incorporation of such data into her story arc and narrative. Her books have been commended for their anthropological authenticity and their ethnobotanical accuracy. However, archaeological research at the time and after the first book was published suggests that some prehistorical details in the series are inaccurate and others fictional, and that specifications of prehistorical milestones are sometimes arbitrary and inconsistent.[citation needed] For example, the differences between Neanderthals and Homo sapiens may have been exaggerated or underestimated in the series; it has been found that Neanderthals had a hyoid bone and may thus have been capable of using vocal language and not as dependent on sign language as portrayed in the series (the existence of a Neanderthal hyoid bone wasn't confirmed until 1983, some years after the first book in the series was published).[citation needed]

The novel also suggests that one of the reasons why the Neanderthals are in decline is because their accumulated knowledge and experience inherited from their ancestors, renders them slower to adapt to the environment than Cro-Magnons, and therefore less able to compete with the more flexible Cro-Magnon. These ideas are directly related to genetic memory. Their spiritual leader is also able to trigger the clan's genetic memories, which extend back to a time prior to the existence of hominids.

A five-year-old girl, who we come to understand is Cro-Magnon, is orphaned and left homeless by an earthquake that destroys her family's camp. She wanders aimlessly, naked and unable to feed herself, for several days. Having been attacked and nearly killed by a cave lion and suffering from starvation, exhaustion, and infection of her wounds, she collapses, on the verge of death.

The narrative switches to a group of people who call themselves "The Clan" and who we come to understand are Neanderthal, whose cave was destroyed in the earthquake and who are searching for a new home. The medicine woman of the group, Iza, discovers the girl and asks permission from Brun, the head of the Clan, to help the ailing child, despite the child being clearly a member of "the Others", the distrusted antagonists of the Clan. The child is adopted by Iza and her brother Creb. Creb is this group's "Mog-ur" or shaman, despite being deformed as a result of the difficult birth resulting from his abnormally large head and the later loss of an arm and leg after being attacked by a cave bear. The clan call her Ayla, the closest they can come to saying her "strange" name. After traveling with them for a while and starting to heal, Ayla wanders away from the group when they stop to discuss what they should do since they haven't found a new home and she discovers a huge, beautiful cave, perfect for them; many of the people begin to regard Ayla as lucky, especially since good fortune continues to come their way as she lives among them.

In Auel's books, the Neanderthal possess only limited vocal apparatus and rarely speak, but have a highly developed sign language. They do not laugh or even smile, and they do not cry; when Ayla weeps, Iza thinks she has an eye disease.

Ayla's different thought processes lead her to break important Clan customs, particularly the taboo against females handling weapons. She is self-willed and spirited, but tries hard to fit in with the Neanderthals, although she has to learn everything first-hand; she does not possess the ancestral memories of the Clan which enable them to do certain tasks after being shown only once.

Iza trains Ayla as a medicine woman "of her line", the most prestigious line of medicine women out of all of the Clans. It takes her much longer to train Ayla than it will her own daughter, Uba, since Ayla does not possess the memories of the Clan. When Ayla grows up, Iza is concerned she will never find a mate and no one will want her, making her a burden to the Clan, so she trains her to be a highly respected medicine women so she will have her own "status" and will not have to rely on the status of a possibly lowly mate.

Ayla's main antagonist is Broud, son of the leader, an egomaniac who feels that she takes credit and attention away from him. As the two mature, the hatred between them festers. When they are young adults, Broud rapes Ayla, but she becomes pregnant, and rejoices in the birth of a son. Her son is almost taken away from her because he seems deformed to the Clan, since he does not look like them and, in the beginning, cannot hold up his head.

The book ends with Creb's death, Broud's succession to the leadership, and his banishment of Ayla, who sets off to find other people of her own kind. She is not allowed to take her son with her. The separation haunts her with guilt and grief for the rest of the series.

The archaeological and paleontological research for this book was carried out by Auel from her public library, by attending archaeological conventions, and touring extensively on sites with briefings by working field archaeologists.[5] Some of the descriptions are based on the first adult Neanderthal skeletons found in Iraq from the cave burial at Shanidar, dating between 60-80,000 years BP. Other data is clearly linked to the widespread Aurignacian culture and Gravettian culture, and their tell-tale Venus figurines which Auel uses as one center of her Cro-Magnon religious practices.[6]

^Auel, various Series forwards, appreciations and credits, esp. "The Shelters of Stone" appreciations make it plain she'd outlined six book series in detail and visited digs in the various locales before this first book, and reprised such visits at various times since.

^Tools and carvings characteristic of these cultures and maps delineating the actual basis dig sites are located within the inside cover art of most of the sequels.